In recent years, flat panel displays have been widely used. Flat panel displays are used in a variety of devices such as liquid crystal televisions, personal computers, cellular phones, digital cameras, personal digital assistants, and portable audio equipment. Displays including liquid crystals, OLEDs, electrophoretic elements, and the like are widely used. An active-matrix display where transistors are arranged in matrix in a pixel portion is presently pervasive.
FIG. 10 is the external view of a substrate used in a conventional display. A substrate 901 used in the conventional display includes a pixel portion 902, a signal line driver circuit (also referred to as a source driver) 904, and a scan line driver circuit (also referred to as a gate driver) 903. In addition, signals and power needed in the scan line driver circuit 903 and the signal line driver circuit 904 are input from the outside through a flexible printed circuit (FPC) 905 (for example, see Reference 1). Here, for the scan line driver circuit 903 and the signal line driver circuit 904, transistors provided over the substrate that are similar to transistors in the pixel portion may be used, or an IC chip may be attached to the substrate by chip on glass (COG).